Hi Don,
At 9:52 PM -0700 6/14/06, Don Wilson wrote:
>Jan,
>
>First, what a great idea to pitch to the builders:
>build three bikes--one with normal tubes, one with OS
>top, and one with oversized down. Cost commitment
>would be big problem for them, but maybe there's a
>grant somewhere that could be had to fund this
>project.
I think some money could be found... but we'd still need the frames
at a good discount. However, the builders name would be attached to
the report, providing good publicity. I think most of my 1500+
readers would love a builder who is interested in making the best
possible bike, rather than following what others do.
>
>Second, if none of them takes you up on it, perhaps
>there is a contemporary mechanical engineer on the
>list addicted to steel lightweights who might CAD
>three identical bikes in a dynamic design simulation
>and make a virtual comparison.
There is an article on that in the latest VBQ. A finite element analysis that uses a CAD model of a frame made from standard diameter True Temper tubing (0.9-0.6-0.9 mm, so it's similar to Columbus SL). The model examines frame flex, and what happens to the energy that goes into the frame as it flexes. The results are quite interesting.
However, one problem with finite analysis models is that the rider cannot adjust their style to the bike. For example, on the Peter Weigle we tested a while ago, I found it worked a lot better for me when I decreased my cadence by about 10 rpm. In the model, you can't optimize your pedal stroke like that. In addition, many of the forces a rider exerts on a bicycle are poorly understood. Thus, it is difficult to incorporate them into a model.
Anybody who has ridden a lot of classic steel frames knows that some feel different from others. These subtle differences are hard to capture in the model.
Jan Heine
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
http://www.vintagebicyclepress.com